Title: Evaluation, Staging, and Surgical Management of Tongue Cancer
Abstract: Cancer of the oral cavity and oropharynx continues to be a public health concern throughout the United States and abroad. The identification of numerous carcinogens, aside from the historically well accepted heavy use of tobacco and alcohol, has contributed to changing demographics of cancer in this region. In fact, the incidence of oral cavity cancers, and tongue cancer in particular, is increasing. The American Cancer Society estimates a total of 34,360 cancers of the oral cavity and pharynx during 2007, including an estimated 9,800 tongue cancers. These figures are slightly higher compared to 2006 statistics that predicted a total 30,990 cancers of the oral cavity and pharynx including 9,040 tongue cancers. While tongue cancer has traditionally been regarded as the oral cavity cancer with the worst prognosis, recent evidence indicates that there is no survival difference between patients with tongue cancer and cancers located at other sites in the oral cavity. This information does not infer that tongue cancer has a favorable prognosis, but rather that oral cavity cancers are inherently of a poor prognosis. It is the purpose of this presentation to review the methods available for evaluation and staging of patients with tongue cancer, as well as the recommended surgical management of these patients, particularly with regard to management of the cervical lymph nodes. The initial evaluation of patients with squamous cell carcinoma of the tongue should involve a clinical examination so as to arrive at a TNM classification and staging. This exercise is important in order to determine the most appropriate form of therapy, particularly with regard to the role of elective or therapeutic neck dissections. In 2007 tongue base cancers are commonly treated with a combined protocol of chemoradiation therapy with curative intent. Oral tongue cancers, however, are commonly operated, with strong consideration given to also operating the clinically negative neck (N0) due to a high incidence of occult cervical lymph node metastases. This incidence of occult neck disease has been estimated at 30-40%, far in excess of the 20% threshold that warrants an elective neck dissection. The N+ neck is clearly indicated for neck dissection. While the clinical examination of the patient is very important, special imaging studies such as PET/CT scans may provide additional information that permits proper surgical planning for the patient. This notwithstanding, these special imaging studies should not supersede the performance of a clinical examination of the neck. Surgical management of the neck in patients with tongue cancer is a function of the clinical examination. In general terms, the clinically negative neck is operated with a supraomohyoid neck dissection (I-III) whereby sentinel lymph nodes are removed en bloc. Some consideration should be given to the extension of the supraomohyoid neck dissection to also remove level IV lymph nodes due to the concern for skip metastases to this oncologic level in some patients. When the neck is classified as N+ it is advisable to perform a type I modified radical neck dissection provided that the spinal accessory nerve can be preserved without violating the capsule of metastatic lymph nodes in this region. The determination as to the need of postoperative radiation therapy is made based on the histologic evaluation of the cervical lymph nodes with an assessment of margins and the presence of perineural invasion in the main tongue specimen.